Conventionally, most analysis of trace molecules relating to clinical diagnosis, food hygiene, and environmental analysis has been carried out at clinical testing laboratories and analysis institutes using automatic analyzers. Such an analyzer includes, for example, an automatic specimen/reagent supply mechanism for supplying a specimen solution and an analysis reagent to a reaction container, reagent holding containers for holding a plurality of reagents, and an automatic cleaning mechanism for cleaning the containers by suction removal of components which are unnecessary for the detection from a liquid mixed in a reaction container. Furthermore, these analyzers need to have a high-precision control mechanism for sequentially operating these mechanisms in combination. Therefore, an automatic analyzer having these mechanisms has been a large and expensive device.
Recently, the importance of simple and fast bedside diagnosis, prevention of accidents before they occur by performing analysis and measurement at the various locations where foods are processed and imported, and performing on-site analysis of toxic substances in rivers and waste products at the river location or waste treatment plant is gaining attention. Consequently, emphasis is being placed on the development of a detection method which can perform measurement simply, rapidly, cheaply, and at a high sensitivity, and on a compact analysis device which can be used to perform on-site analysis and measurement.
In particular, in clinical diagnosis analysis, for early discovery of a sickness condition, an important problem to resolve is how to perform detection with a high degree of sensitivity using a trace amount of the specimen, while simultaneously shortening the analysis time and reducing the amount of specimen required for analysis. To resolve this problem, as a technique for analyzing a trace amount of a target substance in a specimen, new devices are being developed which can perform analysis by applying micro fabrication technology. In such devices, a channel is formed and arranged on a substrate, a liquid such as a blood from a test subject is injected into this channel, and analysis is carried out. For the analysis of a trace amount of specimen using such a device, generally, various techniques have been developed for automatically and sequentially feeding, to signify the presence of a target substance in the specimen, a labeled reagent, such as a fluorescent substance, a radioactive substance, a luminescent substance and the like, a substrate which produces fluorescence and luminescence and absorbs light by an enzyme reaction, a labeled antibody in which an antibody bound to a target substance in a specimen is labeled with an enzyme, a fluorescent substance, a radioactive substance and the like, and various washing solutions.
JP 2006-189374 describes a technique in which a testing cartridge including a plurality of containers and a substrate having a channel arranged on an approximately horizontal face is rotated by centrifugal force, so that a solution is made to move from a container on an inner circumferential side with respect to the axis of rotation to a container on an outer circumferential side with respect to the axis of rotation. However, to sequentially feed a plurality of reagents, a hole has to be drilled in order into the tiny cartridges with a drilling apparatus. Therefore, there are the problems that a precise drilling apparatus is required, and that reducing the size of the device and increasing the speed of analysis is difficult.
JP 2006-121935 describes a technique in which, for automatic measurement of a specimen, analysis is carried out by controlling liquid feeding externally from a chip using a micro feeding device such as a micro pump, and using various valve structures such as a back-flow valve and an active valve, so that a plurality of reagents are sequentially fed to a reaction chamber. However, this technique requires a chip or device mounted with mechanisms which are all complex and precise. This makes operation complex, and fails to resolve the problem of fast, simple and low-costs analysis. Furthermore, there is also the problem that the liquid is contaminated and intermingled with reagents due to liquid stagnating at a connection section with a valve section or a pump.
It could therefore be helpful to provide means capable of sequentially feeding a specimen/reagent (hereinafter sometimes referred to as “liquid”) by utilizing gravity in addition to centrifugal force, which does not require a drilling apparatus, a micro feeding apparatus and the like, and which does not cause contamination or intermingling among reagents.